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Date: Tue, 30 Jun 2020 21:54:48 +0530
From: Vinod Koul <vkoul@...nel.org>
To: Bard Liao <yung-chuan.liao@...ux.intel.com>
Cc: alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
tiwai@...e.de, broonie@...nel.org, gregkh@...uxfoundation.org,
jank@...ence.com, srinivas.kandagatla@...aro.org,
rander.wang@...ux.intel.com, ranjani.sridharan@...ux.intel.com,
hui.wang@...onical.com, pierre-louis.bossart@...ux.intel.com,
sanyog.r.kale@...el.com, slawomir.blauciak@...el.com,
mengdong.lin@...el.com, bard.liao@...el.com
Subject: Re: [PATCH 7/9] soundwire: intel/cadence: merge Soundwire interrupt
handlers/threads
On 24-06-20, 01:35, Bard Liao wrote:
> The existing code uses one pair of interrupt handler/thread per link
> but at the hardware level the interrupt is shared. This works fine for
> legacy PCI interrupts, but leads to timeouts in MSI (Message-Signaled
> Interrupt) mode, likely due to edges being lost.
>
> This patch unifies interrupt handling for all links. The dedicated
> handler is removed since we use a common one for all shared interrupt
> sources, and the thread function takes care of dealing with interrupt
> sources. This partition follows the model used for the SOF IPC on
> HDaudio platforms, where similar timeout issues were noticed and doing
> all the interrupt handling/clearing in the thread improved
> reliability/stability.
>
> Validation results with 4 links active in parallel show a night-and-day
> improvement with no timeouts noticed even during stress tests. Latency
> and quality of service are not affected by the change - mostly because
> events on a SoundWire link are throttled by the bus frame rate
> (typically 8..48kHz).
>
> Signed-off-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> ---
> drivers/soundwire/cadence_master.c | 18 ++++++++++--------
> drivers/soundwire/cadence_master.h | 4 ++++
> drivers/soundwire/intel.c | 15 ---------------
> drivers/soundwire/intel.h | 4 ++++
> drivers/soundwire/intel_init.c | 19 +++++++++++++++++++
> 5 files changed, 37 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
> index 613dbd415b91..24eafe0aa1c3 100644
> --- a/drivers/soundwire/cadence_master.c
> +++ b/drivers/soundwire/cadence_master.c
> @@ -17,6 +17,7 @@
> #include <linux/soundwire/sdw.h>
> #include <sound/pcm_params.h>
> #include <sound/soc.h>
> +#include <linux/workqueue.h>
> #include "bus.h"
> #include "cadence_master.h"
>
> @@ -790,7 +791,7 @@ irqreturn_t sdw_cdns_irq(int irq, void *dev_id)
> CDNS_MCP_INT_SLAVE_MASK, 0);
>
> int_status &= ~CDNS_MCP_INT_SLAVE_MASK;
> - ret = IRQ_WAKE_THREAD;
> + schedule_work(&cdns->work);
> }
>
> cdns_writel(cdns, CDNS_MCP_INTSTAT, int_status);
> @@ -799,13 +800,15 @@ irqreturn_t sdw_cdns_irq(int irq, void *dev_id)
> EXPORT_SYMBOL(sdw_cdns_irq);
>
> /**
> - * sdw_cdns_thread() - Cadence irq thread handler
> - * @irq: irq number
> - * @dev_id: irq context
> + * To update slave status in a work since we will need to handle
> + * other interrupts eg. CDNS_MCP_INT_RX_WL during the update slave
> + * process.
> + * @work: cdns worker thread
> */
> -irqreturn_t sdw_cdns_thread(int irq, void *dev_id)
> +static void cdns_update_slave_status_work(struct work_struct *work)
> {
> - struct sdw_cdns *cdns = dev_id;
> + struct sdw_cdns *cdns =
> + container_of(work, struct sdw_cdns, work);
> u32 slave0, slave1;
>
> dev_dbg_ratelimited(cdns->dev, "Slave status change\n");
> @@ -822,9 +825,7 @@ irqreturn_t sdw_cdns_thread(int irq, void *dev_id)
> cdns_updatel(cdns, CDNS_MCP_INTMASK,
> CDNS_MCP_INT_SLAVE_MASK, CDNS_MCP_INT_SLAVE_MASK);
>
> - return IRQ_HANDLED;
> }
> -EXPORT_SYMBOL(sdw_cdns_thread);
>
> /*
> * init routines
> @@ -1427,6 +1428,7 @@ int sdw_cdns_probe(struct sdw_cdns *cdns)
> init_completion(&cdns->tx_complete);
> cdns->bus.port_ops = &cdns_port_ops;
>
> + INIT_WORK(&cdns->work, cdns_update_slave_status_work);
> return 0;
> }
> EXPORT_SYMBOL(sdw_cdns_probe);
> diff --git a/drivers/soundwire/cadence_master.h b/drivers/soundwire/cadence_master.h
> index b410656f8194..7638858397df 100644
> --- a/drivers/soundwire/cadence_master.h
> +++ b/drivers/soundwire/cadence_master.h
> @@ -129,6 +129,10 @@ struct sdw_cdns {
>
> bool link_up;
> unsigned int msg_count;
> +
> + struct work_struct work;
> +
> + struct list_head list;
> };
>
> #define bus_to_cdns(_bus) container_of(_bus, struct sdw_cdns, bus)
> diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
> index 0a4fc7f65743..06c553d94890 100644
> --- a/drivers/soundwire/intel.c
> +++ b/drivers/soundwire/intel.c
> @@ -1258,21 +1258,7 @@ static int intel_master_probe(struct platform_device *pdev)
> "SoundWire master %d is disabled, will be ignored\n",
> bus->link_id);
>
> - /* Acquire IRQ */
> - ret = request_threaded_irq(sdw->link_res->irq,
> - sdw_cdns_irq, sdw_cdns_thread,
> - IRQF_SHARED, KBUILD_MODNAME, cdns);
> - if (ret < 0) {
> - dev_err(dev, "unable to grab IRQ %d, disabling device\n",
> - sdw->link_res->irq);
> - goto err_init;
> - }
> -
> return 0;
> -
> -err_init:
> - sdw_bus_master_delete(bus);
> - return ret;
> }
>
> int intel_master_startup(struct platform_device *pdev)
> @@ -1344,7 +1330,6 @@ static int intel_master_remove(struct platform_device *pdev)
> if (!bus->prop.hw_disabled) {
> intel_debugfs_exit(sdw);
> sdw_cdns_enable_interrupt(cdns, false);
> - free_irq(sdw->link_res->irq, sdw);
> snd_soc_unregister_component(dev);
> }
> sdw_bus_master_delete(bus);
> diff --git a/drivers/soundwire/intel.h b/drivers/soundwire/intel.h
> index d6bdd4d63e08..bf127c88eb51 100644
> --- a/drivers/soundwire/intel.h
> +++ b/drivers/soundwire/intel.h
> @@ -17,6 +17,8 @@
> * @dev: device implementing hw_params and free callbacks
> * @shim_lock: mutex to handle access to shared SHIM registers
> * @shim_mask: global pointer to check SHIM register initialization
> + * @cdns: Cadence master descriptor
> + * @list: used to walk-through all masters exposed by the same controller
> */
> struct sdw_intel_link_res {
> struct platform_device *pdev;
> @@ -29,6 +31,8 @@ struct sdw_intel_link_res {
> struct device *dev;
> struct mutex *shim_lock; /* protect shared registers */
> u32 *shim_mask;
> + struct sdw_cdns *cdns;
> + struct list_head list;
> };
>
> struct sdw_intel {
> diff --git a/drivers/soundwire/intel_init.c b/drivers/soundwire/intel_init.c
> index ad3175272e88..63b3beda443d 100644
> --- a/drivers/soundwire/intel_init.c
> +++ b/drivers/soundwire/intel_init.c
> @@ -9,6 +9,7 @@
>
> #include <linux/acpi.h>
> #include <linux/export.h>
> +#include <linux/interrupt.h>
> #include <linux/io.h>
> #include <linux/module.h>
> #include <linux/platform_device.h>
> @@ -166,6 +167,19 @@ void sdw_intel_enable_irq(void __iomem *mmio_base, bool enable)
> }
> EXPORT_SYMBOL_NS(sdw_intel_enable_irq, SOUNDWIRE_INTEL_INIT);
>
> +irqreturn_t sdw_intel_thread(int irq, void *dev_id)
> +{
> + struct sdw_intel_ctx *ctx = dev_id;
> + struct sdw_intel_link_res *link;
> +
> + list_for_each_entry(link, &ctx->link_list, list)
> + sdw_cdns_irq(irq, link->cdns);
> +
> + sdw_intel_enable_irq(ctx->mmio_base, true);
> + return IRQ_HANDLED;
> +}
> +EXPORT_SYMBOL(sdw_intel_thread);
Who will call this API? Also don't see header for this..
Is this called from irq context or irq thread or something else?
Also no EXPORT_SYMBOL_NS() for this one?
--
~Vinod
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